Analysis of Moloney murine sarcoma virus (M-MuSV) and Moloney murine leukemia virus (M-MuLV)-associated surface antigens and host immune responses to them. Studies of effects of OK-432 on immune response of normal mice and on the growth of Moloney murine sarcoma virus (M-MuSV)-induced primary tumors in mice of various strains. BIBLIOGRAPHIC REFERENCES: Osugi, Y., Suzuki, S. and Takagaki, Y.: Antitumor and immunosuppressive effects of mycophenolic acid derivatives. Cancer Research 36: 2923-2927, 1976. Kai, K., Ikeda, H., Yuasa, Y., Suzuki, S. and Odaka, T.: Mouse strain resistant to N-, B-, and NB-tropic murine leukemia viruses. J. Virology 20: 436-440, 1976.